Sunday's announcement by the band's rep comes after the 40-year-old frontman had a meltdown onstage at the iHeartRadio Music Festival in Las Vegas on Friday. As Green Day was wrapping up its performance during the all-star, two-day concert, Armstrong profanely complained that the band's time was being cut short.

"One minute left, one minute (expletive) left. You're gonna give me (expletive) one minute? ... I'm not (expletive) Justin Bieber, you (expletives)!" he yelled (although Bieber was not part of the night's festivities).

In a statement to The Associated Press, Green Day apologized "to those they offended at the iHeartRadio Festival" and said its set was not cut short by Clear Channel, the host of the two-day festival.

The Grammy winning band also is canceling some of its promotional appearances. It is due to release the album "Uno" on Tuesday, the follow-up to "21st Century Breakdown," released three years ago. "Uno" is the first in a trilogy of albums; the second is to be out in November, and the last in January. The band is due to kick off a nationwide tour Nov. 26 in Seattle.

Armstrong was hospitalized in early September in Bologna, Italy, for an undisclosed ailment, but recovered well enough to perform at the MTV Video Music Awards on Sept. 6. Since then, the band has made a series of performances, including a "Good Morning America" performance and a New York City concert for the launch of Nokia Music on Sept. 15. No interviews of the band were allowed that evening, but the band chatted with fans and Nokia and AT&T executives before performing for about two hours.

Rock Stars: Then and Now

It's unclear what Armstrong is receiving treatment for; in 2003, he was arrested for DUI, and has acknowledged in the past taking various drugs but has said he now eschews them.

Green Day is one of rock's top acts and had huge success with its 2004 politically charged album "American Idiot," which went on to become a Broadway musical. Armstrong performed for a stretch in the musical.

Most recently, he was a mentor on the NBC talent competition "The Voice."